Widowed and living alone with her son Hisashi, Yuki one day notices her son's penis is abnormally erect. Throbbing intensely, it resembles her late husband's so closely that she finds herself becoming aroused. Deciding to satisfy her desires using her own body, she tries stimulating him with her hands, feet, breasts, and her prized ass, but Hisashi's cock shows no sign of softening. Ultimately, Yuki resolves to deflower her son herself, using her own pussy.